This invention relates to tools and, more particularly, to a hand-held tool for preparing the ends of optical fiber waveguides.
A major impediment to the development of optical communications is the implementation of low-loss splicing and coupling techniques. These techniques require properly prepared fiber ends, meaning that the ends must be smooth, flat, and perpendicular to the fiber axis if high coupling efficiencies are to be obtained. An effective technique for fiber end preparation has been the score-and-break technique, originally designed for use in the laboratory. This technique involves the stretching of the fiber over a curved surface and a light scoring by a hard, sharp edge such as a diamond to produce a microcrack which is diametrically propagated through the fiber to produce a clean break. The curved surface insures a proper break for fibers having a diameter greater than a critical diameter, which for fused quartz is 110 .mu.m, by providing a stress gradient in the stretched fiber. It is not necessary to provide a curved surface, however, if the fiber waveguide has a diameter which is less than this critical value.
It may be appreciated that fiber end preparation is likely to occur under field conditions, and it is therefore desirable to provide a fiber preparation tool which is highly portable and simple to operate. Preferably the tool should be similar to one familiar to service personnel.
One tool which has been developed for carrying out the score-and-break technique in the field is described in an article entitled "Splicing of Optical Fiber Cable on Site" by H. Murata et al. (Procedures of the Fiber Communication Conference; London; September 1975; p. 93.) By means of the tool the fiber is bent at a given radius and held in a tension-applied condition while it is scored and broken. The tool includes a curved fiber-supporting surface, a pair of clamps which secure the fiber to the surface, means for including tension in the fiber, and a wedge-like diamond blade that scores the fiber. The clamps and blade are actuated by a plurality of manually adjustable rod-shaped members which are coupled to an A-shaped mechanism, the legs of which are a pair of manually actuated arms and the lateral element of which is a centrally hinged linkage member. As the arms are squeezed together, the rods are pulled downward by the folding linkage, clamping the fiber to the curved surface and lowering the blade for scoring action on the fiber. The tool construction is complicated. The rod activators must be manually adjusted to achieve both the proper clamping force and blade penetration for various fiber diameters. The difficult construction of this complicated tool is reflected in its high cost.
Another fiber preparation tool for use under controlled conditions is disclosed in an article entitled "Simplified Optical Fibre Breaking Machine" by P. Hensel (Electronics Letters, Vol. 11, No. 24, p. 581 [27 Nov. 1975]). With this tool, a fiber having one end secured to a fixture is secured at its other end to the periphery of a rotatable segmented drum and is tensioned by the rotation of the drum. A cutting blade, working against a dashpot, scores and breaks the tensioned fiber. As stated in the article, the tool is for use under controlled conditions. The tool is larger than a hand tool and comparatively unwieldy.